Approximately 1/3 of opioid addicts are women of childbearing age. Pregnancy during opioid dependence presents a complex array of therapeutic challenges. Methadone is the only maintenance pharmacotherapy currently recommended for use in pregnant opioid-dependent women. Methadone offers many benefits relative to continued untreated heroin addiction or medical detoxification, but its use during pregnancy continues to be controversial due in part to the large percentage of newborns having signs of opioid withdrawal requiring medical intervention and extended hospitalization. Compared to nondrug exposed infants, opioid exposed infants have longer and more costly neonatal hospitalizations and display neurophysiological and behavioral disruptions. It is estimated that 55%-94% of infants exposed to opioids in utero will show signs of opioid withdrawal. Buprenorphine, a new medication under FDA review for the treatment of opioid dependence, is reported to produce only a mild abstinence syndrome following abrupt withdrawal in adults. The efficacy of buprenorphine to produce less neonatal abstinence signs (NAS) in the neonate, compared to methadone, will be assessed in opioid-dependent pregnant women utilizing a randomized, parallel group, multi-site design. The professional expertise of a multi-disciplinary group at Vanderbilt University Medical Center and Middle Tennessee Treatment Center trained in addiction medicine, psychiatry, pediatrics, obstetrics, neonatology, and controlled clinical trials has been brought together to provide comprehensive care for the subjects and rigorous scientific integrity for the study. The Johns Hopkins site will act as the Lead Site of this multi-site trial involving six US sites and two International. Subjects randomized to equivalent opioid doses of methadone (N=30) or buprenorphine (N=30) will be followed through pregnancy. Primary outcome measures are NAS, total anti-withdrawal medication given, and number of neonates treated. Secondary fetal/neonatal outcome measures are: standard antenatal measures, non-stress test, biophysical profile, and length (days) of hospital stay. Secondary maternal outcome measures include: treatment retention, objective and subjective measures of drug use including alcohol, global assessments, and dose-adequacy and safety data. This will be the first study to develop an infrastructure and network of sites with expertise in conducting controlled trials with pharmacotherapies for substance abusing and dependent pregnant women. Utilization of this network will ensure the successful accrual of study participants in a difficult to recruit population (i.e., pregnant women).